Electronic pickup



1942- D. s. DAWSON 2,293,806

ELECTRONIC PICKUP Filed Feb. 3, 1941 2 Sheets-Sheet l /z V 1 M k w /6 /7 /3 /0 /a In venior /6 a Z Dan /4,: p

A iiomey 1942- D. s. DAWSON 2,293,806

ELECTRONIC PICKUP Filed Feb. 3, 1941 2 Sheets-Sheet 2 7 Am? MAG/YET g I n ventor 20. By 2M x A iiorney Patented Aug. 25, 1942 UNITED STATE ELECTRONIC PICKUP Douglas S. Dawson, Wolitown, Va., asslgnor of five per cent to Hugh 8. Ross, Madison, Va., and five per cent to Donald M. Wilhoite, Norfolk, Va.

Application February 3, 1941, Serial No. 377,239

2 Claims.

My invention relates to improvements in electronic pick-up means especially although not necessarily for stringed musical instruments for remote reproduction and amplification of the musical tones of the instrument while being played, and the primary object of the invention is to provide a simpler, more eflicient and less expensive arrangement of the character indicated, which is substantially devoid of background noise, is not affected by the body, capacity of the player Y touching the strings and does not require critical balancing as is the case with magnetic pick-up units using coils in connection with the permanent magnets.

Other important objects and advantages of my invention will be apparent from a reading of the following description and the appended drawings wherein preferred embodiments of my invention are shown for illustrative purposes.

In the drawings:

Figure 1 is a top plan view of one embodiment of my invention applied to a guitar-type of musical instrument.

Figure 2 is a side elevational view of Figure 1.

Figure 3 is an enlarged transverse sectional view taken along the line.33 of Figure 1 and looking in the direction of the arrows.

Figure 4 is a-schematic diagram of an embodiment of the invention involving a midget output transformer preceding the electronic amplifying unit.

Figure 5 is a view similar to Figure 4 showing another embodiment locking said midget output transformer.

Figure 6 is schematic diagram of a further embodiment of the invention using said midget output transformer but being devoid of the electronic amplifier.

The invention by suitable adaptation may be applied to any metal string equipped instrument including the piano and in the case of a violin equipped with graphite coated gut strings. The present invention is also applicable to reproduction of recordings by reverse action so as to reproduce sound appearing in head-phones and loud-speakers, and is thus employable in connection with telephone receivers, hearing aids and loud-speakers for the transmision and reproduction of sound.

Referring in detail to the drawings and first to Figures 1 to 3,-showingthe invention applied to a steel string equipped guitar, the numeral 5 generally designates the body of the guitar including the sounding board 8 having the sound-hole metal nut III on the neck H, the steel strings I2 being stretched between the metal tail-piece 8 and the keys l3 over the bridge 9 and the metal nut l0.

An erect horseshoe-type permanent magnet II has its bight portion secured at IS on a suitable mounting 16 on the back ll of the guitar body to position the poles of the magnet on opposite sides of the strings and just below the strings as shown in Figure 3. In the arrangement shown the magnet is iocated partly in the sound-hole I for convenience in assembling and portions thereof extending through accommodating openings in the sounding board 6. However, other positions of the magnet are feasible, the main consideration being that the magnet be located in such a position that maximum disturbance of the field thereof take place incidental to the vibration of the strings.

A small insulated wire it connects the metal nut III with one side of the primary ll of the midget output transformer l8, as shown in Figure 4, the other side of the transformer primary being connected to the metal tail-piece 8. One side of the primary I! and one side of the secondary I! are connected together as indicated at 20 and bonded to the shield lead to eliminate body capacity when a player touches the strings 12. A shielded conduit 2| which acts as one secondary lead carries the conductor 22 leading from the secondary IQ of the transformer to the electronic amplifier which is generally designated 24, to whose output is connected a suitable loud speaker 25. The transformer [8 may be mounted on the instrument as shown or on the amplifier unit 24.

The embodiment shown in Figure 5 is the same as the embodiment of Figures 1 through 4, except that the small transformer is eliminated.

The embodiment shown in Figure 6 illustrates the employment of single and double bar magnets placed transversely of and substantially parallel to and above and/or below the strings l2. The upper bar magnet is designated 26 and is located sufllciently above the strings l2 to allow the free vibration within the magnetic field. The lower bar magnet 21 underlies the strings I2 and if used in conjunction with an overlying bar magnet 26 is preferably aligned thereunder with the poles reversed.

It will be understood that any of the foregoing embodiments may include or exclude the midget output transformer shown herein as l8 or l8.

Although I have shown and described herein preferred embodiments of my invention, I do not I, the metal tail-piece 8, the bridge 9, and the wish to limit the application of the invention thereto, except as may be necessary in view of the scope of the subioined claims. What is claimed as new is:

1. In combination a spaced pair of metal terminals, a plurality of; vibratory conductive magnetically permeable strings stretched between and in electrical engagement with said metal terminals whereby the corresponding end portions of all 01' the strings are electrically connected togetherby the metal terminals, a permanent magnet in whose field freely vibrating portions of a the strings intermediate their ends vibrate, amplifying means, and shielded connections between said metal terminals and the input of said amplifying means.

2. In combination a spaced pair of metal terminals, a plurality of vibratory conductive magnetically permeable strings stretched between and in electrical engagement with said metal terminals whereby the corresponding end portions of all of the strings are electrically connected together by the metal terminals, a permanent magnet in whose field freely vibrating portions oi the strings intermediate their ends vibrate, amplifying means,

and shielded connections between said metal connected to the shield of said shielded electricalconnections, so as to eliminate body static of a body used to vibrate the strings.

DOUGLAS S. DAWSON. 

